The present invention relates to a new and improved construction of a key-operated, electrical switching device with magnets enclosed in series in a key body and a key guide connected to the switching device casing and along which is arranged a row of electrical switching contacts operable by the magnets, it being possible to produce a predetermined electrical main connection through the magnetic operation of at least that contact located in the final position in the row in the key insertion direction, whilst in the penultimate position in the row is provided a magnetically operable blocking contact.
A switching device of this type is known from U.S. Pat. No. 4,331,013 and fulfils the switching in theft-proof manner the circuit of the electrical system of a motor vehicle. For this purpose the casing of the known device contains a plurality of equidistantly spaced magnet-operated switches and for making the desired electrical connection only the switches selected by the electrical circuit diagram in accordance with a coded diagram are switched on, so that permanent magnets invisibly enclosed within the key body have to be provided at the appropriate position for the same. This connection remains interrupted on operating also provided magnet-operated switches, which have not been selected for producing this connection.